diff options
| author | Martin Kuchta <martin.kuchta@netapp.com> | 2018-08-27 18:54:46 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2018-08-27 19:09:50 +0200 |
| commit | 2b47bb9cba048e778a7d832f284feccb14a40483 (patch) | |
| tree | d9a348f3f78e3494214d0af38e118f41d34e3cb8 | |
| parent | 2dab17550dd464bcf531088efa81a9d595167f2a (diff) | |
| download | glibc-2b47bb9cba048e778a7d832f284feccb14a40483.tar.gz glibc-2b47bb9cba048e778a7d832f284feccb14a40483.tar.xz glibc-2b47bb9cba048e778a7d832f284feccb14a40483.zip | |
pthread_cond_broadcast: Fix waiters-after-spinning case [BZ #23538]
(cherry picked from commit 99ea93ca31795469d2a1f1570f17a5c39c2eb7e2)
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | NEWS | 1 | ||||
| -rw-r--r-- | nptl/pthread_cond_common.c | 8 |
3 files changed, 15 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog index 7fcb7d5981..eeb2d87032 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2018-08-27 Martin Kuchta <martin.kuchta@netapp.com> + Torvald Riegel <triegel@redhat.com> + + [BZ #23538] + * nptl/pthread_cond_common.c (__condvar_quiesce_and_switch_g1): + Update r to include the set wake-request flag if waiters are + remaining after spinning. + 2018-07-29 H.J. Lu <hongjiu.lu@intel.com> [BZ #23459] diff --git a/NEWS b/NEWS index bc150b63f9..a2e31b45cc 100644 --- a/NEWS +++ b/NEWS @@ -89,6 +89,7 @@ The following bugs are resolved with this release: [23363] stdio-common/tst-printf.c has non-free license [23456] Wrong index_cpu_LZCNT [23459] COMMON_CPUID_INDEX_80000001 isn't populated for Intel processors + [23538] pthread_cond_broadcast: Fix waiters-after-spinning case Version 2.27 diff --git a/nptl/pthread_cond_common.c b/nptl/pthread_cond_common.c index 8e425eb01e..479e54febb 100644 --- a/nptl/pthread_cond_common.c +++ b/nptl/pthread_cond_common.c @@ -405,8 +405,12 @@ __condvar_quiesce_and_switch_g1 (pthread_cond_t *cond, uint64_t wseq, { /* There is still a waiter after spinning. Set the wake-request flag and block. Relaxed MO is fine because this is just about - this futex word. */ - r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1); + this futex word. + + Update r to include the set wake-request flag so that the upcoming + futex_wait only blocks if the flag is still set (otherwise, we'd + violate the basic client-side futex protocol). */ + r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1) | 1; if ((r >> 1) > 0) futex_wait_simple (cond->__data.__g_refs + g1, r, private); |